Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 998 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
2. 2.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) putting the iron away (d) cutting the lemon
3. 3.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
5. 5.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
6. 6.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
7. 7.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) ironing the paper
8. 8.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) lemon juice (d) an adult with an iron
11. 11.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
12. 12.True or false: plugging in the iron is a job for an adult. (a) False (b) True
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a balloon (d) lemon juice
14. 14.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) white paper (d) an adult with an iron
17. 17.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
19. 19.True or false: writing the message is a job a child can do. (a) True (b) False
20. 20.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a battery cell (d) a mirror
21. 21.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
22. 22.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
23. 23.True or false: letting the paper dry is a job for an adult. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same paper (c) how dark the writing is (d) the same cotton bud
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) lemon juice (d) a small bowl
27. 27.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) cutting the lemon (d) ironing the paper
28. 28.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) white (d) green
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
33. 33.True or false: putting the iron away is a job a child can do. (a) True (b) False
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
35. 35.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
36. 36.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a cotton bud (d) white paper
38. 38.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) it gets darker (d) writing turns green
39. 39.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice

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